Variable thermal insulation assembly

ABSTRACT

A variable thermal insulation assembly includes at least one array comprising a plurality of sheets of film, wherein the plurality of sheets are in a stacked arrangement and each sheet is bonded to an adjacent sheet along a plurality of longitudinally extending regions such that each pair of adjacent sheets form a plurality of longitudinally extending cavities between adjacent regions of the adjacent sheets, a support frame comprising end elements, wherein the support frame frames the plurality of sheets, wherein support frame is coupled to the array to support the array such that the array may transition between an expanded state in which the array is expanded, and a compressed state in which the array is compressed, within the plane of the frame along the direction perpendicular to the longitudinal axis such that the longitudinally extending cavities are expanded or compressed, wherein in the expanded state, the front edge conforms to one of the second end of the support frame or a second front edge of a second array to form a seal that inhibits air flow between the front edge and the one of the second end of the support frame or the second front edge of the second array.

TECHNICAL FIELD

The present disclosure relates to a variable thermal insulation assemblythat includes a plurality of thermal cell arrays that are adjustablebetween an expanded state and a compressed state.

BACKGROUND

During sunny weather conditions it is often desirable to maximize thetransmission of sunlight into a building to assist with both lightingand heating of the interior of the building. By contrast, during dark,cloudy, or cold weather conditions it is often desirable to maximize thethermal insulation of a building to minimize heat loss from thebuilding. Windows are typically employed in buildings to facilitate thetransmission of sunlight into the building while also providing a sealedbarrier against the entry of wind, rain, snow and other undesirableelements. While windows typically provide a relatively high degree ofoptical transmission which may be advantageous for sunny weatherconditions, they also typically provide a relatively low degree ofthermal insulation which may be undesirable for dark, cloudy, or coldweather conditions.

Attempts have been made to develop solutions that provide both a highdegree of optical transmission and a high degree of thermal insulation.However, many of these solutions have failed to provide sufficientsunlight transmission or thermal insulation, require frequent adjustmentthroughout the day, are costly, or are overly complex.

SUMMARY OF THE INVENTION

The disclosure provides a variable thermal insulation assembly thatincludes an array of air-enclosing cavities or pockets, referred toherein as thermal cells, that is adjustable between an expanded stateand a compressed state. In the expanded state, the variable thermalinsulation assembly provides a thermally insulating layer, whereas inthe compressed state, the variable thermal insulation assembly retractssuch that the thermal insulation provided is reduced relative to theexpanded state. In some embodiments, the variable thermal insulationassembly may be installed in association with a window such that, in theexpanded state, light transmission through the window may be reducedrelative to the compressed state, in which light is transmitted throughthe window. The array of thermal cells is referred to herein as athermal cell array.

One aspect of the disclosure provides a variable thermal insulationassembly that includes a frame that circumscribes a thermal actuationregion having a gas, one or more thermal cell array units positionedwithin the thermal actuation region, each thermal cell array unitincluding a first surface sheet and a second surface sheet, wherein thefirst and second surface sheets are similarly shaped and define athermal cell array region therebetween, a thermal cell array positionedwithin each thermal cell array region and coupled to the first andsecond surface sheets such that the thermal cell array substantiallyfills the thermal cell array region, wherein each thermal cell arraycomprises a plurality of sheets and at least two of the sheets in eachthermal cell array are flexible sheets, wherein adjacent pairs of saidflexible sheets are bonded together along at least one pair of bondingregions that extend substantially parallel to each other such that eachpair of flexible sheets defines at least one substantiallylongitudinally symmetrical cavity between each pair of bonding regions,each longitudinally symmetrical cavity being one of a plurality ofthermal cells, wherein a distance between each pair of bonding regionsis sufficiently small that the total heat loss arising from convectivegas flow within the thermal cells is less than total heat loss arisingfrom thermal conduction of the gas present within the thermal actuationregion, wherein the distance between each pair of bonding regions issufficiently large, and the thermal conductivity of the sheets issufficiently low, such that heat transfer due to thermal conductionwithin the sheets is less than the heat loss due to thermal conductionof the gas of the thermal actuation region, wherein each of theplurality of thermal cells is bonded to another thermal cell or a sheetin order to form a connected thermal cell array unit, a positioncontroller coupled to at least one of the first and second surfacesheets for applying a control force on at least one of the first andsecond surface sheets to expand the thermal cell array into an expandedstate and compress the thermal cell array into a compressed state withinthe thermal actuation region to vary a volume of the thermal actuationregion that is occupied by the thermal cell array units, wherein theplurality of sheets are sufficiently thin and formed of one or morematerials that are sufficiently compliant such that, for each first andsecond sheet, when the thermal cell arrays are in the expanded state bythe applied control force, a gap between each surface sheet and theadjacent frame surface or surface sheet, is made sufficiently small thatthe total heat loss that is attributable to gas flow through the gap isless than the total of the heat loss due to thermal conduction throughthe thermal cells.

In a further aspect, the position controller is coupled to the one ofthe first and second sheets such that, when the control force isapplied, the at least one of the first and the second surface sheetsmove in a direction that is normal to the one of the first and secondsurface sheet such that, during the moving the first and second surfacesheets are maintained substantially parallel to each other.

In a further aspect, the position controller is coupled to the one ofthe first and second surface sheets such that, when the control force isapplied, the one of the first and second surface sheets pivots whereby afirst end of the one of the first and second surface sheet issubstantially fixed relative to a corresponding first end of the otherof the first and second surface sheets, and a second end of the one ofthe first and second surface sheets, opposite the first end, movesrelative to the second end of the other of the first and second surfacesheets.

In a further aspect, at least some of the plurality of sheets comprisingthe thermal array are coated on at least a first side by a layer ofmaterial having a thermal emissivity of less than 0.2.

In a further aspect, the material is aluminum.

In a further aspect, each of the plurality of sheets comprising thethermal array has a curved shape, and the plurality longitudinallyextending regions follow the curved shaped such that the formedlongitudinally extending cavities have the curved shape.

In a further aspect, the support frame further comprises a front paneland a back panel coupled to the edge elements to form an enclosed panelthat encloses the array.

In a further aspect, the front panel and back panel arelight-transmitting window elements fabricated that are fabricated fromone of glass, mylar, acrylic, polycarbonate, polyethylene, or ethylenetetrafluoroethylene.

In a further aspect, light-transmitting window elements are diffuselylight-transmitting elements.

In a further aspect, the front panel and the back panel are each formedfrom a thin, light-transmitting material, wherein the front panel andthe back panel are bonded together in a periphery region to define apillow-shaped cavity within the enclosed panel.

In a further aspect, the thin, light transmitting material is one ofpolyethylene, polycarbonate, or ethylene tetrafluoroethylene.

In a further aspect, the enclosed panel further includes a vent utilizedfor increasing a pressure within the enclosed panel for increasing astructural rigidity of the enclosed panel.

In a further aspect, a volume defined by the enclosed panel is filledwith an inert gas.

In a further aspect, the inert gas is argon gas.

In a further aspect, an inner surface of at least one edge element has areflectivity of at least 80%.

In a further aspect, the inner surface of the at least one edge elementhas a convex profile.

In a further aspect, edge elements comprise a first end element at thefirst end, a second end element at the second end, and a pair of sideelements that connect the first and second end elements, wherein atleast one of the side elements includes a seal element for inhibitingairflow through an opening of the plurality of longitudinally extendingcavities adjacent to the side element when the array is in the expandedstate.

In a further aspect, the seal element is a first inflatable bladder.

In a further aspect, one of the first end element and the second endelement includes a second inflatable bladder coupled to the firstinflatable bladder by an air-transfer connection to transfer air betweenthe first inflatable bladder and the second inflatable bladder, whereinthe air-transfer connection is configured to inflate the firstinflatable bladder and deflate the second inflatable bladder when thearray is in the expanded state, and inflate the second inflatablebladder and deflate the first inflatable bladder when the array in thecompressed state.

In a further aspect, the variable thermal insulation assembly includes aposition controller for transitioning the array between the expandedstate and the compressed state.

In a further aspect, the position controller is an electrostatic systemwherein the plurality of sheets of the thermal cell array are formed ofan electronically insulative material that is coated on one side with anelectrically conductive material such that, for each pair of sheets, theelectrically conductive material coating of each flexible sheet of thepair are separate by at least one layer of the electrically insulativematerial, the

the variable thermal insulation assembly further including a controllerto apply an electric potential difference between each adjacent pairs ofsheets such that the electrically conductive coatings of the adjacentpair of sheets attract each other to cause the array to be in thecompressed state, and a plurality of biasing elements located with theplurality of longitudinally extending cavities to bias adjacent pairs ofsheets away from each other to cause the array to be in the expandedstate in the absence the controller applying an electrical charge.

In a further aspect, the plurality of biasing elements are provided byforming the plurality of flexible sheets from an elastomeric material,wherein the elastomeric material is deformed such that the plurality offlexible sheets are biased into the expanded state.

In a further aspect, the light-transmitting window elements have a firstportion that is diffusely light transmitting and a second portion thatis non-diffusely light transmitting such that the diffusioncharacteristics of the transmitted light can be controlled.

In a further aspect, each thermal cell consists of two flexible filmelements, each flexible film element having two edge-bond zones thatcomprise less than 20% of a surface area of the flexible film element,each edge-bond zone extending in a direction parallel to thelongitudinal direction of the flexible film element, and a central bondzone comprising less than 20% of the surface area and extending parallelto the longitudinal direction along the center of the flexible filmelement, each thermal cell is formed by bonding two flexible filmelements along the edge bond zones, thermal cells are oriented intostacks for which each thermal cell is bonded to an adjacent thermal cellalong the central bond zone, and a plurality of said stacks are orientedwithin the thermal cell region such that the stacks do not make contactwith one another even when thermal cell array unit is in the compressedstate.

In a further aspect, additional thin sheets similar in size and shape tothe first and second surface sheets, are positioned within said stacksand bonded there along the film element central bond zones, in order tostabilize the stacks against lateral motion within the stack duringcontrolled movement of the first and/or second sheets.

In a further aspect, the plurality of sheets are sufficiently thin andformed of one or more materials that are sufficiently compliant suchthat an average size of the gap, when the thermal cell array is in theexpanded state, is less than 5 mm.

In a further aspect, the plurality of sheets are sufficiently thin andformed of one or more materials that are sufficiently compliant suchthat the average size of the gap, when the thermal cell array is in theexpanded state, is less than 0.5 mm.

Another aspect of the present disclosure provides a variable thermalinsulation assembly that includes at least one array comprising aplurality of sheets of film, wherein the plurality of sheets are in astacked arrangement and each sheet is bonded to an adjacent sheet alonga plurality of longitudinally extending regions such that each pair ofadjacent sheets form a plurality of longitudinally extending cavitiesbetween adjacent regions of the adjacent sheets, a support framecomprising end elements, wherein the support frame frames the pluralityof sheets, wherein support frame is coupled to the array to support thearray such that the array may transition between an expanded state inwhich the array is expanded by extending a front side of the arraywithin a plane of the supporting frame in a direction from a first endof the support frame to a second end of the support frame, the directionbeing perpendicular to a longitudinal axis of the longitudinallyextending regions, such that the longitudinally extending cavities areexpanded to provide thermal insulation over the support frame, and acompressed state in which the array is compressed within the plane ofthe frame along the direction perpendicular to the longitudinal axissuch that the longitudinally extending cavities are compressed, whereinin the expanded state, the front edge conforms to one of the second endof the support frame or a second front edge of a second array to form aseal that inhibits air flow between the front edge and the one of thesecond end of the support frame or the second front edge of the secondarray.

In a further aspect, one end of the plurality of longitudinallyextending cavities are fixed in a closed position such that a transitionbetween the compressed state and the expanded state is a pivotingmotion.

In a further aspect, each of the plurality of sheets comprise aplurality of separate portions such that adjacent portions of a sheetare bonded together at the longitudinally extending region.

In a further aspect, wherein the thickness of the array in thecompressed state is less than 20% of the thickness of the array in theexpanded state.

In a further aspect, the thickness of the array in the compressed statein less than 5% of the thickness of the array in the expanded state.

In a further aspect, the front side of the array is sufficientlycompliant such that the front edge conforms to form a seal between thearray and adjacent elements at low pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described, by way ofexample only, with reference to the attached figures, in which:

FIGS. 1A and 1B are top cross-sectional views of a thermal cell arrayunit configured in an expanded state and a compressed state,respectively, according to an embodiment;

FIGS. 1C and 1D are front elevation cross-sectional views of the thermalcell array unit according to the embodiment shown in FIG. 1A with thearray in an expanded state and a compressed state, respectively;

FIG. 2A depicts a side elevation view of a rectangular thermal cellarray unit;

FIG. 2B depicts a schematic 30° oblique view of a rectangular thermalcell array unit configured in an insulative state according to theembodiment shown in FIG. 2A;

FIG. 2C depicts a side elevation view of a curved thermal cell arrayunit side elevation view;

FIG. 2D depicts a schematic 30° oblique view of a curved thermal cellarray unit configured in an insulative state according to the embodimentshown in FIG. 2C;

FIG. 3A is a diametric view of an enclosed panel, labeling the top,bottom, side and front elements according to an embodiment;

FIGS. 3B and 3C show front and top views of the enclosed panel, andlabels the direction of expansion and compression of the thermal cellarray unit according to the embodiment shown in FIG. 3A;

FIGS. 4A and 4B show the front and side views of an enclosed panelaccording to an embodiment with the thermal cell array unit fullycompressed and depicts that the sunlight is transmitted through thepanel;

FIGS. 4C and 4D show the front and side views of an enclosed panelaccording to the embodiment shown in FIG. 4A with the thermal cell arrayunit fully expanded and depicts that the sunlight is not transmittedthrough the panel;

FIG. 5A is an exploded view showing the components of an enclosed panelcontaining a thermal cell array unit according to an embodiment;

FIGS. 5B and 5C are diametric views of an enclosed panel according tothe embodiment of FIG. 5A with the thermal cell array unit in theinsulative state and the transmissive state, respectively;

FIG. 6 depicts a cross-sectional view of an enclosed panel having curvedinterior surfaces according to an embodiment;

FIG. 7 depicts a cross-sectional view of an enclosed panel wherein thethermal cell array unit surface sheet conforms to a curved frame elementaccording to an embodiment;

FIGS. 8A and 8B depict 30° oblique views of an enclosed panelincorporating an inflatable bladder according to an embodiment, whereinthe bladder is shown in a deflated state and an inflated state,respectively;

FIGS. 9A and 9B depict front elevation cross-sectional views of anenclosed panel incorporating a two-part inflatable bladder systemaccording to an embodiment;

FIGS. 10A through 10C depict different configurations of thermal cellarray units within an enclosed panel according to various embodiments;

FIG. 11 depicts a cross-sectional view of a thermal cell array unitenclosed within a pillow-like enclosure according to an embodiment;

FIG. 12 depicts a threaded rod component for expanding and compressing athermal cell array unit according to an embodiment;

FIG. 13 shows a detailed view of a drive wire wrapped around a threadedrod component for expanding and compressing a thermal cell array unitaccording to an embodiment;

FIG. 14 is an exploded view showing the components of an enclosed panelcontaining a thermal cell array unit and various position controlcomponents according to an embodiment;

FIG. 15 is an isometric view of a thermal cell array unit supported bywires according to the embodiment shown in FIG. 14;

FIG. 16 depicts a method of attaching a thermal cell array unit surfacesheet to a drive wire according to an embodiment;

FIGS. 17A through 17D depict alternate methods for expanding andcompressing a thermal cell array unit according to various embodiments;

FIG. 18 depicts a method of supporting a thermal cell array unit usingrollers according to an embodiment;

FIG. 19 depicts a method of supporting a thermal cell array unit usinghanging supports according to an embodiment;

FIG. 20 depicts a method of supporting a thermal cell array unit using acentrally-located wire according to an embodiment;

FIGS. 21A through 21C depict several front plate designs according tovarious embodiments;

FIGS. 22A and 22B are top cross-sectional views of one cavity of athermal cell array unit that includes an electrostatic positioncontroller according to an embodiment;

FIGS. 23A and 23B are top cross-sectional views of one cavity of athermal cell array unit according to the embodiment shown in FIGS. 22Aand 22B incorporating a separate spring-like element according to anembodiment;

FIGS. 24A and 24B are top cross-sectional views of a thermal cell arrayunit according to the embodiment shown in FIGS. 22A and 22B.

FIGS. 25A through 25C depict a building structure with an isoscelespeaked roof according that incorporates a thermal cell array unit;

FIG. 26 depicts a building structure with an isosceles peaked roofaccording to the embodiment shown in FIGS. 25A through 25C;

FIGS. 27A through 27C depict a building structure with a sawtooth peakedroof that incorporates a thermal cell array unit;

FIGS. 28A through 28C depict a building structure with a curved roofthat incorporates a thermal cell array unit.

FIGS. 29A and 29B are top-down cross-sectional views depictingconfigurations of thermal cell array units within an enclosed panelwhereby the expansion and compression is achieved through a pivotingmotion;

FIGS. 30A and 30B are top cross-sectional views of a thermal cell arrayunit with individual thermal cell units, configured in an expanded stateand a compressed state, respectively;

FIGS. 31A and 31B are top cross-sectional views of a thermal cell arrayunit with individual thermal cell units separated by sheets, configuredin an expanded state and a compressed state, respectively.

DETAILED DESCRIPTION

The embodiments described in the present disclosure relate to a variablethermal insulation assembly that includes an adjustable thermal cellarray unit. In some embodiments the variable thermal insulation assemblyis configured such that the thermal cell array unit may be adjustablebetween a thermally insulative expanded state and an opticallytransmissive compressed state.

Referring to FIGS. 1A and 1B, top cross-sectional views of a firstembodiment of a thermal cell array unit 100 are shown. The thermal cellarray unit, alternatively referred to herein as an “array unit”,generally comprises the thermal cell array, alternatively referred toherein as an “array”, and the first and second surface sheets. The arrayunit 100 generally comprises a first surface sheet 140, a second surfacesheet 150 and a thermal cell array 115 that is comprised of a pluralityof flexible sheets 120 a-k that are generally arranged in a stackedarrangement. Although the example shown in FIGS. 1A through 1D includeseleven flexible sheets 120 a-k in the thermal cell array, the thermalcell array may include more or less than eleven flexible sheets 120 a-k.

The thermal cell array 115 is positioned in a region 145 between thefirst and second surface sheets 140 and 150, which may be describedherein as the “thermal cell array region 145”. As described in moredetail below, the thermal cell array unit 100 is generally positioned ina thermal actuation region in order to provide variable thermalinsulation within that thermal actuation region. Generally speaking, thethermal actuation region will contain air or other gases or gasmixtures.

Surface sheets 140 and 150 are similarly shaped such that when surfacesheets 140 and 150 are positioned as close as possible to one another inthe maximally compressed state, both the gaps between sheets 140 and 150and the distances between adjacent edges of surface sheets 140 and 150are small relative to the overall size of surface sheets 140 and 150.When surface sheets 140 and 150 are aligned as such, gaps betweensurface sheets 140 and 150 and the distances between adjacent edges ofsurface sheets 140 and 150 are preferably less than 1/10 of the overalldimension of the sheet. As an example, for a rectangular sheet with alength and width dimension, where the width is smaller than the length,surface sheets 140 and 150 are considered similarly sized if gapsbetween surface sheets 140 and 150 and the distances between adjacentedges of surface sheets 140 and 150 are preferably less than 1/10 of thesheet width dimension. As described in more detail below with referenceto FIG. 7, the surface sheets 140 and 150 may each have, for example, aconvex shape.

The flexible sheets 120 a-k, which may alternatively be referred toherein simply as sheets, may be formed of layers of thin, flexiblereflective film. The sheets 120 a-k may be any suitable thin, flexiblefilm material including, for example a metallic film, aluminizedpolyester film, aluminized Mylar, or any low thermal conductivity or lowcost reflective films. Sheets 120 a-k may be coated on one or both sidesby a thin metallic coating or other low emissivity coating. It may bedesirable that the thermal emissivity of the material coating the sheets120 a-k is less than 0.2, and more desirably less than 0.05, recognizingthat investments made in reducing this ratio will have diminishingeconomic terms because of the very minimally changing loss associatedwith thermal conduction of the gas.

Surface sheets 140 and 150 may be formed of the same material and coatedin the same manner as sheets 120 a-k, or they may be formed from adifferent flexible film material. Each sheet 120 a-k is bonded to anadjacent sheet 120 a-k along a plurality of longitudinally extendingbonding regions 130. For example, sheet 120 a is bonded to sheet 120 b,as shown in FIG. 1A. The bonding regions 130 of pairs of adjacent sheetsform a plurality of parallel longitudinally extending thermal cells 110.As such, each pair of flexible sheets 120 a-k define at least onesubstantially longitudinally symmetrical thermal cell 110 between eachpair of bonding regions 130. The term longitudinal symmetry refers to astructure that has a longitudinal direction and has the characteristicthat the cross sectional shape of the structure in planes that areorthogonal to the structure's longitudinal direction, is substantiallyuniform. The bonding regions 130 may be generally linear regions thatare directed into the page in the views shown in FIGS. 1A and 1B. Thebonding utilized to form bonding regions 130 may be provided by anysuitable means including adhesive that is deposited as a liquid andsubsequently cured, adhesive strips or films, ultrasonic bonding,thermal bonding, and chemical bonding such as solvent welding.

In the example shown in FIGS. 1A through 1D, the surface sheets 140 and150 are bonded to the thermal array formed by sheets 120 a-k alonglongitudinally extending bonding regions 130 in a similar manner assheets 120 a-k are bonded to one another. Alternatively, other methodsof bonding the surface sheets 140 and 150 may be utilized such as, forexample, bonding the surface sheets 140 and 150 in a bonding region thatextends over substantially all of the area of the surface sheets 140 and150, or in bonding regions that are not longitudinally extending.

Adjacent thermal cells 110 formed from the same pair of sheets 120 a-kare sealed from adjacent thermal cells 110 along the longitudinal edgeby the bonding in bonding regions 130. Each thermal cell 110 is bondedeither to at least one other thermal cell 110 or is bonded to anadjacent sheet 120 a-k that is also bonded to at least one otheradjacent thermal cell to form a connected thermal cell array.

The sealing between adjacent thermal cell 110 need not be hermeticallysealed. Additionally, the ends of the thermal cell 110, along the edgesof the sheets 120 a-k extending perpendicular to the longitudinal axisof the bonding regions 130, may also be sealed closed. The width of eachair-enclosing thermal cell 110, i.e., the spacing between bondingregions 130, may be less than 5 cm, and more desirably less than 1 cmsuch that an insignificant amount of thermally-induced convective flowoccurs within each thermal cell 110.

The thermal cell array 115 is attached to surface sheets 140 and 150 insuch a manner that as the distance between surface sheets 140 and 150 isincreased by means of an applied control force applied by a positioncontroller (not shown) coupled to at least one of the surface sheets 140and 150, the shape of the thermal cells 110 expand so that the thermalcell array 115 substantially fills the thermal cell array region 145between the surface sheets 140 and 150. In this expanded state of thearray, the array fully occupies the thermal actuation region. FIGS. 1Athrough 1D show an example in which the thermal cell array unit 100 isexpanded along a direction perpendicular to the longitudinal axisdefined by the longitudinally extending bonding regions 130 orcompressed by compressing the array in the opposite direction. FIGS. 1Cand 1D show front-elevation cross-sectional views of array unit 100 thatcorrespond to FIGS. 1A and 1B, respectively. In the views shown in FIGS.1A and 1B, the sheets 120 a-k extend in the direction into the page, andthe longitudinally extending regions that are bonded extend in thedirection into the page.

Expanding the array unit 100 causes the thermal cells 110 to expand, asshown in FIG. 1A and is described herein as the expanded state, andcompressing the array unit 100 causes the thermal cells 110 to compress,as shown in FIG. 1B and is described herein as the compressed state. Airflows into the thermal cells 110 when the array unit 100 is expanded andair is forced out of the thermal cells 110 when the array unit 100 iscompressed. In the expanded state, the array unit 100 may act as athermal insulator due to the air-enclosing pockets.

The size of the thermal cells is determined by the distance between eachpair of bonding regions 130 comprising the thermal cell array 115. Thisdistance between bonding regions 130 is sufficiently small that thetotal heat loss arising from convective gas flow within the thermalcells 110 is less than total heat loss arising from thermal conductionof the gas present within the thermal actuation region. Furthermore, thedistance between each pair of bonding regions 130 is sufficiently large,and the thermal conduction of the sheets is sufficiently low, that heattransfer due to thermal conduction within the sheets is less than theheat loss due to thermal conduction of the gas. Accordingly, theprocedure for determining the acceptable range for the distance betweeneach pair of bonding regions 130 is either by experimental testing andthermal loss measurements, or by thermal modeling software. In eithercase, it will be found that if this distance is too large, thermalconvection will be enabled within the thermal cells and will contributeexcessively to thermal loss, and in contrast, if the distance is toosmall, the conductivity of the sheets will contribute excessively tothermal loss, because the distance along the sheet that heat must flowbecomes smaller and this allows greater heat loss. Ideally, it will bepossible to ensure that the heat loss from thermal convection and fromthermal conduction of the sheets will be less than 25% of the intrinsicheat loss associated with thermal conduction of the gas present in thethermal cells. In typical applications, the ideal range for the distancebetween the bond regions is greater than 10 mm and less than 50 mm.

As described in more detail below, the array unit 100 in the expandedstate may be expanded to cover a window, for example, to provideinsulation when desired, and may be compressed into the compressed statewhen insulation is not desired, such that the array is compressed sothat it no longer covers the window, allowing light to enter a building.

When compressed, the array unit 100 generally possesses a thickness thatis significantly less than when the array unit is in the expanded state.In many applications, the overall thickness of the array unit in thecompressed state is about 25% or less, and desirably less than 5%, ofthe thickness of the array unit 100 in the fully expanded state.

FIGS. 2A and 2B depict the shape of a rectangular thermal cell arrayunit 200. Array unit 200 can be expanded and compressed along adirection (shown as arrow 202 in FIG. 2B) perpendicular to thelongitudinally extending regions to transition between the expanded andcompressed states as shown in FIGS. 1A and 1B, respectively. In someapplications, rectangular profile 210, with the longitudinally extendingregions running parallel to the edge 220 is desirable. For example,rectangular profile 210 may be desirable in a structure formed usingsteel or aluminum frame elements that support flat rectangular panels orwindows, as is common in some types of greenhouse construction.

FIGS. 2C and 2D depict the shape of a curved thermal cell array unit.Array unit 230 can be expanded and compressed along a direction (shownby arrow 204) perpendicular to longitudinally extending regions totransition between the expanded and compressed states as shown in FIGS.1A and 1B, respectively. In some applications, curved profile 240, withlongitudinally extending regions extending in a direction parallel tocurved sides 250 is desirable. For example, curved profile 240 may bedesirable in a structure formed using curved steel or aluminum frameelements that support curved rectangular panels, windows, or sheetmaterial, as is typical for construction of greenhouses often describedas hoop houses or Quonset hut greenhouses. Curved segment 250 maycomprise an arc of a circle but need not be restricted to an arc of acircle. The preferred shape of the curved segments may be determined bythe shape of the structure into which the curved elements areincorporated.

Generally, the array unit 100 is supported within a support frame 300 toform a variable thermal insulation assembly 350. Support frame 300circumscribes a thermal actuation region in which the array unit 100 ispositioned. Referring to FIG. 3A, an example support frame 300 is shown.The support frame 300 provides a means of supporting or otherwiseorienting the array unit 100 appropriately for its given application.One or more thermal cell array units 100 may be positioned within thethermal actuation region circumscribed by support frame 300 and theseone or more thermal cell array units 100 may be supported by one supportframe 300.

The support frame 300 includes edge elements 302, 304, 306, and 308.Elements 302 and 306 may be referred to as side elements, element 304may be referred to as a top element, and element 308 may be referred toas a bottom element. The support frame 300 may optionally include afront window 310 and a back window 312 to form an enclosed panel thatfully enclose the thermal actuation region, as described in more detailbelow. The enclosed panel may be suitable for providing, for example, amulti-paned window or a skylight structure. The terms side, top, bottom,front, and back are utilized herein to refer to the orientation shown inthe particular figures referred to, and are not intended to be otherwiselimiting.

FIGS. 3B and 3C show front and top views, respectively, of a variablethermal insulation assembly 350 that includes an array unit 100 coupledto and within a support frame 300. The array unit 100 may be expandedand compressed within the support frame in the direction illustrated byarrow 320 to transition between the expanded and compressed states. Inthis embodiment, a position controller (not shown) is coupled to thefirst of the two surface sheets (not shown). When the control force isapplied to the thermal unit by the position controller, the firstsurface sheet moves in a direction that is normal to the first surfacesheet such that, during the motion, the first and second surface sheetsare maintained substantially perpendicular to one another. This desiredmotion may be ensured by inclusion of a variety of structural linearconstraint elements, including low friction bearings, rollers, tracks,support wires and guides. The array unit 100 shown in FIGS. 3B and 3C isin a partially compressed state for illustrative purposes.

The array unit 100 shown in FIGS. 3B and 3C may be coupled at one end314 to the array unit 100 to the side element 306 such that the end 316that is opposite the end that is coupled to the side element 306 may be,for example, pulled or pushed to transition the array unit between theexpanded state and the contracted state. The end 314 of the array unit100 that is coupled to the side element 306 may be either end that runsparallel to the longitudinally extending bonding regions 130 tofacilitate expanding the cavities 110 to expand the array unit 100 alongthe direction 320. In the arrangement shown in FIGS. 3B and 3C, theoutermost surface sheet at the end 314 of the array unit 100 remains ina substantially fixed position relative to the support frame 300 duringexpansion and compression of the array unit 100.

When the array unit 100 is expanded, it may press against any of theedge elements 302, 304, 306, and 308, or against adjacent similarlyexpanded array units 100 in the case that multiple array units areprovided within the support frame 300, such that the array unit and thesupport frame or adjacent array unit against which it expands forms anair flow attenuation structure that that sufficiently reduces air flowthrough the gap, thus sufficiently reducing heat loss caused by airexfiltration and/or convective air flow. The plurality of sheets aresufficiently thin and formed of one or more materials that aresufficiently compliant that no additional pressure is required toachieve the desired air flow attenuation than that which is alreadyneeded to reliably expand the array unit. This air flow attenuationstructure achieved by the sufficiently compliant array is required toachieve the desired insulation targets using practical methods forcontrolling the expansion and compression of the array unit. The desiredairflow attenuation structure is achieved when the average, oreffective, physical size of the gap between the expanded array unit andthe adjacent support frame element or array unit has a dimension lessthan 5 mm and ideally less than 0.5 mm. The force per unit area of thesurface sheets of the thermal cell array units that is required toreliably expand the array unit depends on the dimensions (in particularthe thickness of sheets 120 a-k and the dimensions of air-enclosedpockets 110) and material composition (in particular the Young's modulusof sheets 120 a-k) of the array. Typically, the value of this desiredpressure per unit area will be in the range 1,000 to 10,000 Pa.

FIGS. 4A and 4B show a front and a side view of an array unit 100 withina support frame 300, with the array unit 100 in a fully compressedstate. The support frame 300 may be an enclosed panel that includesfront and back windows, as described in more detail below. As shown inFIGS. 4A and 4B, when the array unit 100 is in the fully compressedstate, the support frame 300 is substantially open and sunlight,represented by arrows 400 may be transmitted through the support frame300. FIGS. 4C and 4D show the array unit 100 and support frame 300 fromFIGS. 4A and 4B with the array unit 100 in a fully expanded state. Asshown in FIGS. 4C and 4D, when the array unit 100 is in the fullyexpanded state, the support frame 300 is substantially closed by thearray unit 100 and sunlight, represented by arrows 402, is substantiallyinhibited from passing through the support frame 300.

An example of an enclosed panel 500 utilized to form a variable thermalinsulation assembly 501 is shown in FIGS. 5A and 5B. FIG. 5A shows anexploded view of the components of the enclosed panel 500. Support frameelements 501 a, 501 b, 502 a, and 502 b form a rectangular supportframe, similar to support frame 300 described above. Window elements 503a and 503 b are supported by frame elements 501 a, 501 b, 502 a, and 502b by an adhesive layer (not shown), a retaining edge groove (not shown),or any other suitable method for attaching the window elements 503 a and503 b to the support frame. Window elements 503 a and 503 b may befabricated from a material with high light transmission such as, forexample, as glass, acrylic plastic, ethylene tetrafluoroethylene sheet,or polycarbonate plastic sheeting. The material utilized for windows 503a and 503 b may desirably be a material that can be cleaned periodicallyto remove dust and dirt that may collect on the exterior surfaces ofwindow elements 503 a and 503 b. In other embodiments, the material forwindow elements 503 a and 504 b may not have high light transmissionproperties such as, for example translucent material that diffusetransmitted light. Alternatively the window elements 503 a and 503 b maybe an opaque material such that the enclosed panel 500 may be utilizedas a wall panel rather than as a window.

The diffusion characteristics of the transmitted light are determined bythe degree of diffusion caused by the light-transmitting panes as thelight passes through the pane. A diffusing pane, for example one madefrom glass or plastic having a milky-white appearance, causessubstantially collimated light to become substantially un-collimated asit passes through the pane. A non-diffusing pane, for example one madefrom highly transparent glass or plastic, causes substantiallycollimated light to maintain its collimation as it passes through thepane. The desired diffusion characteristics of the transmitted light canbe achieved by selecting appropriate optical characteristics for thelight-transmitting panes of the panel housing the thermal cell arrayunit, and appropriately expanding and compressing selected array unitswithin the overall variable thermal insulation assembly. For example,for a greenhouse structure incorporating multiple panels, a portion ofthe light-transmitting panels may incorporate diffusing panes andanother portion of the light-transmitting panels may incorporatenon-diffusing panes. In this example, if it is desirable for thetransmitted light to be diffused, the array units adjacent the diffusingpanes can be compressed and the array units adjacent the non-diffusingpanes can be expanded. This will cause light to enter predominatelythrough the diffusing panes only. Similarly, if it is desirable for thetransmitted light to be non-diffused, the array units adjacent thediffusing panes can be expanded and the array units adjacent thenon-diffusing panes can be compressed. This will cause light to enterpredominately through the non-diffusing panes only.

Frame elements 501 a, 501 b, 502 a, and 502 b need not be opticallytransparent and may desirably be fabricated using materials with lowthermal conductance. The frame elements 501 a, 501 b, 502 a, 502 b,which may be substantially similar to elements 306, 302, 308, and 304,respectively, of support frame 300 described previously, and the windowelements 503 a and 503 b of the enclosed panel 500 define a thermalactuation region, that houses a thermal cell array unit 504, such as thearray unit 100 described above. As shown in FIG. 5B, the thermal cellarray unit 504 may be expanded into an expanded state that fills theenclosed cavity to facilitate the enclosed cavity 500 providing thermalinsulation. FIG. 5C shows enclosed panel 500 with thermal cell arrayunit 504 compressed into a compressed state to reduce the area of thewindow elements 503 a and 503 b that are blocked to increase the amountof incident light transmitted through the enclosed panel 500. Thespecific size and shape of enclosed panel 500 will depend on theapplication. The enclosed panel 500 may be, for example, 60 cm wide, 200cm tall and 15 cm thick. These example dimensions have been specifiedhere because they are consistent with the size of rectangular frameelements in typical steel or aluminum frame greenhouse construction. Inthis example panel, the perimeter to area ratio is sufficiently smallthat heat loss along the edges of the panel would be minimal. Theexample panel is not so large, however, as to be difficult orinconvenient for handling during manufacturing, assembly orinstallation. It is anticipated that a wide range of panel dimensionscould be appropriate for different applications.

For a given application, the desired thermal insulation value of thearray unit 100 or the enclosed panel 500 can be achieved by adjusting anumber of parameters, including, for example, the number of layers ofthin, flexible film used to fabricate the thermal cell array unit,choice of whether the thin, flexible film is coated on one side or onboth sides with a thin layer of low thermal emissivity material, byenclosing an appropriate gaseous medium (such as argon) within thethermal cells of the array unit 504, and by adjusting the degree towhich the 504 array unit forms a barrier or air flow attenuationstructure with the adjacent frame elements 501 a, 501 b, 502 a, and 502b in the enclosed panel 500 at all points along the array unit's 504periphery to prevent transfer of heat through either exfiltration of airor gas or convective flow. Air flow is attenuated by sufficientlyreducing the size of the gap between the surface sheet and the adjacentframe surface or surface sheet of an adjacent thermal cell array unit.The gap is reduced to a sufficiently small amount such that the amountof heat loss caused by air flow through the gap around the edges of thethermal cell array unit 504 is less than, and ideally much less than,the heat loss due to thermal conduction through the thermal cell arrayunit 504.

In the case where a gaseous medium is used, the air inside the enclosedpanel 500 would be replaced with this gaseous medium. The enclosed panel500 may or may not be pressurized. In some applications it may beappropriate for the panel 500 to be pressurized and in otherapplications it may be necessary to incorporate a pressure release valve(not shown) in such a way that the heat transfer associated with thepressure adaptation is reduced.

When the array unit is in an expanded state, the insulation valueachieved is greater than when the array unit is in the compressed state.In many applications, in the expanded state it is desirable that theinsulation value is at least R-5 (RSI 0.88) and preferably at least R-15(RSI 2.64).

In some applications, it may be desirable to increase the transmissionof light through the enclosed panel 500. In many applications, it isdesirable that in the compressed state preferably at least 70%, andideally at least 90%, of the incident light is transmitted through thepanel 500. There are a number of features which can be incorporated intoan enclosed panel 500 in order to increase light transmission throughthe enclosed panel 500 when the array unit 504 is in the compressedstate. Referring to FIG. 5A, light transmission may be increased bydecreasing the thickness of the frame elements 501 a, 501 b, 502 a, and502 b of the enclosed panel 500, thereby increasing the fraction of thetotal panel face area occupied by transparent window elements 503 a and503 b. Light transmission may also be increased by causing the interioror inward-facing surfaces of frame elements 501 a, 501 b, 502 a, and 502b to have highly light-reflective characteristic. This can be achieved,for example, by adhering or otherwise applying a thin layer of highlyreflective material and preferably highly specularly reflective materialto the interior or inward-facing surfaces of frame elements 501 a, 501b, 502 a, and 502 b. The reflectance of the highly reflective materialmay desirably be at least 80%, which is a typical reflectance value forinexpensive vapour-deposited aluminum coatings. A skilled person wouldunderstand that other modifications to the enclosed panel 500 may bepossible, in addition to, or alternative to, the above describedfeatures.

In some applications, it may be desirable to minimize the length of edge510 of the thermal cell array unit 504. Referring to the embodimentdepicted in FIG. 5A, the enclosed panel 500 side frame elements 501 aand 501 b that are substantially longer than end frame elements 502 aand 502 b, and further if thermal cell array unit 504 expands andcompresses by moving between side frame elements 501 a and 501 b.Because it may be more difficult to reliably achieve adequate air flowattenuation along the sliding edge of the thermal cell array unit, i.e.,the sides adjacent to end frame elements 502 a and 502 b in FIG. 5A,having the sliding edge of thermal cell array unit 504 moves along theshorter dimension of enclosed panel 500 as shown in FIG. 5A may bedesirable to provide greater air flow attenuation compared to anarrangement in which the thermal cell array unit 504 moves between endframe elements 502 a and 502 b.

Light transmission may also be increased by causing interior frameelements 502 a and 502 b to have a curved profile in order to cause thelight reflected by frame elements 502 a and 502 b to transmit throughwindow element 503 b within a desirable angular range. FIG. 6 depicts across-sectional view of an enclosed panel 600, which may be similar toenclosed panel 500 described above, as a means of illustrating thismethod of increasing light transmission. Note that FIG. 6 is not shownto scale, but rather the vertical dimension is somewhat exaggeratedrelative to the horizontal dimension, in order to more easily illustratethe key feature described below.

The enclosed panel 600 shown in FIG. 6 includes frame elements 601 a and601 b and window elements 602 a and 602 b. A curved, reflective element605 is adhered or otherwise attached to frame element 601 a. FIG. 6depicts enclosed panel 600 operating in the transmissive state, i.e.,the thermal cell array unit (not shown) in a compressed state. In thecompressed state, most light rays incident on window element 602 a passthrough window element 602 a, travel without encountering an opticalobstruction through the air cavity between window elements 602 a and 602b, and transmit through window element 602 b into the buildingstructure. A fraction of the light rays incident on window element 602 aencounter curved reflective element 605 after passing through windowelement 602 a.

FIG. 6 depicts two example light rays encountering curved reflectiveelement 605. Incident light ray 603 a encounters curved reflectiveelement 605, and reflects such that it follows the path indicated bytransmitted light ray 603 b. Incident light ray 604 a encounters curvedreflective element 605, and reflects such that it follows the pathindicated by transmitted light ray 604 b. Light rays 603 a and 604 afollowed the same angular path when they transmit through window element602 a, but after reflecting from curved reflective element 605, theyfollowed different angular paths when they transmit through windowelement 602 b. The range of angles of transmitted light may at leastpartially be adjusted by altering the shape of curved reflective element605.

It may be desirable for the variable thermal insulation assembly toachieve high thermal insulation characteristics, and high thermalinsulation characteristics are achieved by reducing heat transfer acrossthe thermal cell array unit. When the thermal cell array unit isarranged in the expanded state, it is preferable that there be minimalair gaps between the edges of the thermal cell array unit and thesupport frame elements of the enclosing panel, in order to reduce heatloss by air exfiltration through these gaps. The degree of required airflow attenuation depends in part on the desired application andcharacteristics of the enclosed panels. For example, the enclosed panelsmay or may not be well sealed, and a building structure itself may ormay not be well sealed. Note that it may not be necessary to minimizeair gaps at all edges of the thermal cell array unit. Depending on thephysical orientation of the array unit (that is, whether it is orientedwith the window elements parallel to the horizon, perpendicular to thehorizon, or at some intermediate angle in between parallel andperpendicular to the horizon) it may be preferable to reduce air gapsat, for example, three of four edges of the thermal cell array unit. Forexample, a larger air gap along one edge of the array unit 504 wouldallow for differential thermal expansion of components comprising anenclosed panel according to, for example, the example enclosed panel 500shown in FIGS. 5A through 5C, while also reducing heat loss via airexfiltration through gaps between the thermal cell array unit and thecomponents of the enclosing panel.

An example for reducing the air gap between the thermal cell array unitand the enclosing panel elements is shown in in FIG. 7. Note that FIG. 7is not shown to scale, but rather the vertical dimension is somewhatexaggerated relative to the horizontal dimension, in order to moreeasily illustrate the key feature described here. FIG. 7 depictsenclosed panel 700 that includes frame elements 701 a and 701 b. Athermal cell array unit 702, which may be substantially similar to arrayunit 100 described above, is contained within the interior cavity ofenclosed panel 700 and is shown in FIG. 7 in a partially expanded state.A first surface sheet 703 is attached to a front edge 706 of the thermalcell array unit 702, and a second surface sheet 708, forming a back edgeof the thermal cell array unit 702, is coupled to frame element 701 b.In the example shown in FIG. 7, the surface sheet 704.

Surface sheet 703 may be fabricated from a thin and/or flexible sheetmaterial such as mylar, polycarbonate, acrylic, or polyethylene. In thecompressed state, surface sheet 703 conforms to the shape of frameelement 701 b. Note that while FIG. 7 depicts frame element 701 b ashaving a curved shape, frame element 701 b need not be curved. Surfacesheet 703 may have light-reflecting characteristics, so that whenthermal cell array unit 702 is compressed against frame element 701 b toachieve the transmissive state, incoming light rays that encountersurface sheet 703 will reflect from surface sheet 703 and transmit intothe building structure. Surface sheet 703 may have specularly reflectivelight-reflecting characteristics or diffusely reflectivelight-reflecting characteristics.

Dotted lines 704 a, 704 b, 704 c, 704 d, and 704 e depict the differentprofile and position of surface sheet 703 over time, as thermal cellarray unit 702 is expanded to fill the cavity within enclosed panel 700.When thermal cell array unit 702 is fully expanded, and therefore in theexpanded state, the flexible surface sheet 703 may substantially conformto the curved shape of frame element 701 a, reducing the air gap betweenthe thermal cell array unit 702 and the frame element 1001 a, forming anair flow attenuation structure.

As described earlier, the array unit is sufficiently compliant that noadditional pressure is required to achieve the desired air flowattenuation than is already needed to expand the array unit. This airflow attenuation structure achieved by the sufficiently compliant arrayunit is required to achieve the desired insulation targets usingpractical methods for controlling the expansion and compression of thearray unit. The desired airflow attenuation structure is achieved whenthe average or effective physical gap between the expanded array unitand the adjacent support frame element or array unit has a dimensionless than 5 mm and ideally less than 0.5 mm. The pressure required toexpand the array depends on the dimensions (in particular the thicknessof the sheets comprising the array and the dimensions of air-enclosedpockets) and material composition (in particular the Young's modulus ofsheets comprising the array) of the array. As mentioned previously, wellknown techniques for experimentally measuring heat loss for modellingheat loss using available software make it readily possibly to determinethe acceptable values for the sheet parameters in order to comply withthe requirements stated.

In another example, an air gap between the thermal cell array unit andthe frame components may be reduced using a seal element. This sealelement may be an inflatable bladder located on an inner surface of asupport frame element and that expands when the array unit is in theexpanded state. FIGS. 8A and 8B show an example enclosed panel 800 thatincludes an inflatable bladder 801. The thermal cell array unit is notshown in FIGS. 8A and 8B for simplicity. When the array unit is in thecompressed state, the inflatable bladder 801 is deflated, as shown inFIG. 8A, to inhibit obstruction of light passing through the enclosedpanel 800 by the bladder 801. When the array unit is in the expandedstate, the inflatable bladder 801 may be inflated to reduce a gapbetween the edges of the array unit and the edge element 802, providinga seal that inhibits air flow between the edges of the array unit andthe edge element 802 of the enclosed panel 800. The inflatable bladder801 may be included, for example, on an edge element 802 that isadjacent to an edge of the array unit that includes the open ends of thelongitudinal air pockets such that inflating the bladder 801 provides aseal at these open ends.

In this example, the array unit, such as array unit 100 shown in FIGS.1A through 1C, would have longitudinally extending regions orientedvertically such that the bladder would provide a seal along a lower edgethat includes openings of the horizontally extending air-pockets. Inother examples, more than one inflatable bladder 801 may be provided,each bladder on a respective edge element of the enclosed panel 800 toprovide a seal along more than one edge. Inflatable bladder 801 may beinflated by an air pump or other pneumatic pressure-generating device(not shown), contained partly or fully inside enclosed panel 800, orfully outside enclosed panel 800.

Referring to FIGS. 9A and 9B, another example is shown in which air gapsbetween the thermal cell array unit and the frame components may bereduced using a two-part inflatable bladder system. FIGS. 9A and 9B showan enclosed panel 900 that includes a thermal cell array unit 901contained within the cavity of enclosed panel 900, a first inflatablebladder 902 coupled to an inner surface of a first edge element 904 anda second inflatable bladder 903 coupled to a second edge element 905that is perpendicular to the first edge element. The thermal cell arrayunit 901 may be substantially similar to array unit 100 described above.FIGS. 9A and 9B are not shown to scale, and in particular the size ofthe second inflatable bladder 903 is exaggerated relative to the firstinflatable bladder 902 for illustrative purposes.)

Inflatable bladders 902 and 903 may share an air-transfer connection(not shown) such that air can transfer between the two bladders. Whenthe array unit 901 is in the compressed state as shown in FIG. 9A, thefirst inflatable bladder 902 is deflated to inhibit obstruction ofincoming light, and the second inflatable bladder 903 is inflated. Whenthe array unit is in the expanded state as shown in FIG. 9B, the firstinflatable bladder 902 is inflated and the second inflatable bladder 903is partially deflated. In operation, when the thermal cell array unit901 reaches a fully expanded state, a front edge 906 of the thermal cellarray unit 901 presses against the second inflatable bladder 903, whichcauses air from the second inflatable bladder to be pushed through theair-transfer connection into the first inflatable bladder 902, andcausing the first inflatable bladder 902 to inflate. The firstinflatable bladder 902 in its inflated state provides a seal to reducethe gap between the edge 907 of the thermal cell array unit 901, whichincludes the open ends of the longitudinally extending air-pockets ofthe array unit 901, and the edge element 904 of the enclosed panel 900,inhibiting air flow through the gap between edge 907 and edge element904 and through the open ends along edge 907 of the thermal cell arrayunit 901.

In some applications, it may be desirable to have a particularconfiguration of one or more thermal cell array units contained withinan enclosed panel. FIGS. 10A through 10C depict different configurationsof thermal cell array units within an enclosed panel. In the exampleshown in FIG. 10A, enclosed panel 1000 a contains one thermal cell arrayunit 1003 as described above. In the example enclosed panel 1000 a,thermal cell array unit 1003 is compressed toward frame element 1001 ato transition to the compressed state. In the expanded state, thethermal cell array unit 1003 is expanded in the direction from frameelement 1001 a to frame element 1002 a such that thermal cell array unit1003 fills the enclosed panel 1000 a.

In another example, shown in FIG. 10B, enclosed panel 1000 b contains afirst thermal cell array unit 1004 and a second thermal cell array unit1005. In this example, in the compressed state, thermal cell array unit1004 is compressed toward frame element 1002 b and thermal cell arrayunit 1005 is compressed toward frame element 1001 b such that thethermal cell array units 1004 and 1005 are located at opposing ends ofthe enclosed panel 1000 b. In the expanded state, thermal cell arrayunit 1004 is expanded toward frame element 1001 b, and thermal cellarray unit 1005 is expanded toward frame element 1002 b such that theexpanded thermal cell array units 1004 and 1005 meet in a center regionof the enclosed panel 1000 b. Thermal cell array units 1004 and 1005 inthe expanded state may press against each other along respective frontedges 1006 and 1008, forming an air flow attenuation structure. One orboth of the front edges 1006 and 1008 may include surface sheets (notshown) substantially similar to surface sheet 703 that conforms when thethermal cell array units 1004 and 1005 meet in order to form an air flowattenuation structure.

In another example, shown in FIG. 10C, enclosed panel 1000 c containsone thermal cell array unit 1010 that is arranged in a center region ofthe enclosed panel 1000 c. In this example, thermal cell array unit 1010is compressed from both the front edge 1012 and the back edge 1014toward the center of the region of the enclosed panel 1000 c totransition into the compressed state. To transition to the expandedstate (not shown), the thermal cell array unit 1006 is expanded suchthat the front edge 1012 moves toward frame element 1002 c and the backedge 1014 moves toward frame element 1001 c. In other examples, theenclosed panel may contain more than two thermal cell array units, andthe arrangement of the thermal cell array units may include anycombination of the above described example arrangements.

Referring now to FIG. 11, an example enclosed panel 1100 is shown thatis formed by appropriately shaping a thin optically-transparent filmmaterial. The example enclosed panel 1100 shown in FIG. 11 is formed bybonding a pair of thin optically-transparent films 1101 a and 1101 b atbond regions 1102 to form pillow-shaped air cavity 1104 that encloses athermal cell array unit 1103. The view shown in FIG. 11 is across-sectional view and, in practice, each bond region 1102 enclosesone or more thermal cell array units 1103. In this embodiment, the bondregions 1102 and the films 1101 a and 1102 b form the elements of theenclosed panel, analogous to, for example, the elements 501 a, 501 b,502 a, 502 b, 503 a, and 503 b of the enclosed panel 500 described abovewith reference to FIG. 5.

Films 1101 a and 1101 b may be formed from any suitable materialincluding, for example, polyethylene, polycarbonate, and ethylenetetrafluoroethylene. Films 1101 a and 1101 b are bonded in bond region1102 by any suitable means including, for example, adhesive tape, epoxy,ultrasonic bonding, and thermal bonding. Thermal cell array unit 1103may be substantially similar to the array unit 100 described above. Thepillow-shaped air cavity 1104 may be formed by using air pressure toinflate enclosure 1100 after the films 1101 a and 1101 b are bondedtogether. The enclosure 1100 may include, for example, a vent (notshown) to facilitate adjusting the amount of pressure within the cavity1104, and thereby adjusting the corresponding degree of inflation ofenclosure 1100. For example, in an embodiment where enclosure 1100 formsthe exterior structure of the building structure, rather than beingsupported by the exterior structure of the greenhouse, it may bedesirable to increase the degree of inflation of enclosure 1100 toprovide more structural rigidity in the event of inclement weather. Forexample, the pressure within the enclosure 1100 may in increased bypumping air into a vent (not shown) in advance of inclement weather toprovide greater rigidity, and may be decreased, by removing air throughthe vent, to reduce rigidity once the inclement weather has passed.

In order for the assembly to transition between the compressed state andthe expanded state, it is necessary to have a means of causing thethermal cell array unit to expand and compress. While particular methodsof expanding and compressing the thermal cell array unit are describedhere, other methods may be apparent to a person skilled in the art.

One example of a position controller for expanding and compressing thethermal cell array unit is a mechanical system using drive wires thatare attached to either the thermal cell array unit or attached to asurface sheet which is further attached to the thermal cell array unit.These drive wires are subsequently attached to a mechanical driveassembly such that the drive wires can be moved in one direction tocause the thermal cell array unit to expand and the drive wires can bemoved in a second, opposite direction to cause the thermal cell arrayunit to compress.

The mechanical drive assembly may include a rotating drive rod,preferably having a circular cross-section, upon which the drive wirescan be wound and unwound. FIG. 12 depicts an example of one suchrotating drive rod. Example drive rod 1200 comprises two sections 1201 aand 1201 b. In the example shown in FIG. 12, grooved sections 1201 a and1201 b have spiral grooves or threads machined into the outsideperimeter of the rod, to facilitate winding and unwinding of the drivewires (not shown). The grooves in grooved sections 1201 a and 1201 b arenot easily visible in FIG. 12, but are shown in detail in FIG. 13. Driverod 1200 further comprises mounting sections 1202 and 1203, which slideinto low friction mounting brackets (not shown) that attach drive rod1200 to the frame elements forming the enclosed panel (not shown).Mounting sections 1202 and 1203 may have a smaller diameter than groovedsections 1201 a and 1201 b to facilitate low frictional movement withinthe mounting brackets. Drive rod 1200 further comprises end mountsection 1204, which attaches to an end mounting bracket (not shown). Endmount section 1204 may have spiral grooves or threads machined into theoutside perimeter of the section, to facilitate rotation of drive rod1200. Drive rod 1200 is rotated by connecting it to the rotating shaftof a motor (not shown). Drive wires (not shown) are attached to driverod 1200 by connection screws 1205. The diameter of end mount section1204 may be smaller than the diameter of grooved sections 1201 a and1201 b.

A detailed view of connection screws 1205 are shown on FIG. 13, wherethey are labeled 1305 and 1306. FIG. 13 shows a portion of groovedsection 1300 (labeled 1201 a in the depiction shown in FIG. 12).Referring to FIG. 13, the left end 1302 of drive wire 1307 is connectedto grooved section 1300 by pressing it between connection screw 1305 andflat area 1301 machined into grooved section 1300. Drive wire 1307 isthen wrapped around grooved section 1300 such that the wire is containedwithin the surface grooves. Drive wire 1307 is then pulled away fromgrooved section 1300 along the path labeled as 1303 a in order toconnect it to other components within the mechanical positioncontroller, which may also be referred to as an actuation system for thethermal cell array unit (not shown). Drive wire 1307 then returns to thegrooved section along the path labeled as 1303 b. (Although it is notshown, paths 1303 a and 1303 b form a continuous loop of drive wire1307.) Drive wire 1307 is then again wrapped around grooved section 1300such that the wire is contained within the surface grooves. The rightend 1304 of drive wire 1307 is connected to grooved section 1300 bypressing it between connection screw 1306 and flat area 1308 machinedinto grooved section 1300.

FIG. 14 is an exploded view of an enclosed panel 1400 containing variouscomponents of a position controller. Low friction mounting brackets 1402and 1403 and end mounting bracket 1404 are attached to frame element1407. Drive rod 1401 is attached to frame element 1407 by mountingbrackets 1402 and 1403 and end mounting bracket 1404. Low friction wireguide elements 1406 are attached to frame element 1407. Low frictionwire guide elements 1406 may be, for example, pulleys or other lowfriction elements. Drive wires (not shown) wind around drive rod 1401 asdescribed with reference to FIG. 13, and loop through wire guideelements 1406. Protective dome 1405 surrounds drive rod 1401. Thethermal cell array unit contained within the enclosed panel is not shownin FIG. 14.

FIG. 15 shows a view of the fully assembled enclosed panel, according toFIG. 14. Thermal cell array unit 1501 is contained within enclosed panel1500. Drive wires 1502 are attached to thermal cell array unit 1501 byconnecting drive wires 1502 to surface sheet 1503. Surface sheet 1503shown in FIG. 15 may also be referred to as front plate 1503. Thermalcell array unit is depicted in FIG. 15 in the partially expanded state.FIG. 15 depicts ten separate drive wires, spaced at approximatelyregular intervals. The number and relative position of the drive wiresdepicted in FIG. 15 is intended as an example only. The appropriatenumber and relative position of the drive wires may be different than asshown in FIG. 15, depending on a number of factors, including but notlimited to: the size and shape of the enclosed panel, the orientation ofthe enclosed panel within a building structure, the intended purpose ofthe panel, and the desired operational characteristics of the panel.

FIG. 16 depicts a detailed view of one example of a method of attachingthe thermal cell array unit front plate to a drive wire, so that thedrive wire can vary the spatial location of the front plate and therebycause the thermal cell array unit to which the front plate is connectedto expand or compress as desired. In the example shown in FIG. 16, drivewire 1602 passes through hole 1603 in front plate 1601. Hole 1603 has adiameter slightly larger than drive wire 1602. Hole 1603 is spatiallypositioned near the edge of front plate 1601. Drive wire 1602 is securedin position within hole 1603 by mechanical positioning elements 1604 and1605. Mechanical positioning elements may be a crimp, bead, curedadhesive droplet, or other means of mechanically locking drive wire 1602in positon within hole 1603.

A rotating drive rod as described above is one example of a mechanicalmethod of expanding and compressing the thermal cell array unit. FIGS.17A-17D depict components related to alternate mechanical methods forexpanding and compressing a thermal cell array unit. FIG. 17A depicts atop-down view of pulley system 1701. Pulley system 1701 comprises afirst pulley 1702 a and a second pulley 1702 b. First pulley 1702 a andsecond pulley 1702 b are co-planar. Drive wire 1703 forms a continuousloop, following a path defined by the position of pulleys 1702 a and1702 b. A first pulley assembly as shown in FIG. 17A may be positionedabove the thermal cell array unit (not shown) and a second pulleyassembly as shown in FIG. 17A may be positioned below the thermal cellarray unit (not shown). The top of the front plate (not shown) of thethermal cell array unit (not shown) may be connected at one location todrive wire 1703 for the pulley assembly positioned above the thermalcell array unit. The bottom of the front plate (not shown) of thethermal cell array unit (not shown) may be connected at anotherdifferent location to drive wire 1703 for the pulley assembly positionedbelow the thermal cell array unit. A motor or other mechanical drivingmechanism (not shown) connected to either of pulley 1702 a or 1702 bcauses the front plate to move in a desired direction, thereby causingthe thermal cell array unit to expand or compress.

FIG. 17B depicts a top-down view of pulley system 1704. Pulley system1704 comprises pulley 1705 and drive wire 1711. Drive wire 1711 forms acontinuous loop, following a path defined by the position of pulley 1705and an appropriate assembly of low-friction wire guides or pulleys (notshown). The front plate (not shown) of the thermal cell array unit (notshown) may be connected in one location to drive wire 1711. A motor orother mechanical driving mechanism (not shown) connected to pulley 1705causes the front plate to move in a desired direction, thereby causingthe thermal cell array unit to expand or compress.

FIG. 17C depicts a top-down view of pulley system 1706. Pulley system1706 comprises pulley 1707, low-friction wire guides 1708 a and 1708 band drive wire 1712. Wire guides 1708 a and 1708 b may be stationaryelements or may be rotating elements such as idler pulleys. Drive wire1712 forms a continuous loop, following a path defined by the positionof pulley 1707, wire guides 1708 a and 1708 b, and an appropriateassembly of low-friction wire guides or pulleys (not shown). The frontplate (not shown) of the thermal cell array unit (not shown) may beconnected in one location to drive wire 1712. A motor or othermechanical driving mechanism (not shown) connected to pulley 1707 causesthe front plate to move in a desired direction, thereby causing thethermal cell array unit to expand or compress.

FIG. 17D depicts a top view of pulley system 1709. Pulley system 1709comprises a first pulley 1710 a, a second pulley 1710 b, a first drivewire 1713 and a second drive wire 1714. Drive wire 1713 forms acontinuous loop, following a path defined by the position of pulley 1710a and an appropriate assembly of low-friction wire guides or pulleys(not shown). Drive wire 1714 forms a continuous loop, following a pathdefined by the position of pulley 1710 b and an appropriate assembly oflow-friction wire guides or pulleys (not shown). The front plate (notshown) of the thermal cell array unit (not shown) may be connected inone location to drive wire 1713 and in another, different, location todrive wire 1714. A first assembly of pulley system 1709 may bepositioned above the thermal cell array unit (not shown) and a secondassembly of pulley system 1709 may be positioned below the thermal cellarray unit. Using this approach, drive wires 1714 may be connectedappropriately to all four corners of the thermal cell array unit frontplate (not shown) to cause smoother or more controlled motion. A motoror other mechanical driving mechanism (not shown) connected to both offirst pulley 1710 a and second pulley 1710 b causes the front plate tomove in a desired direction, thereby causing the thermal cell array unitto expand or compress.

The appropriate method of causing the thermal cell array unit to expandand compress may be different than as described in the precedingexamples, depending on a number of factors, including but not limitedto: the size and shape of the enclosed panel, the orientation of theenclosed panel within a building structure, the intended purpose of thepanel, and the desired operational characteristics of the panel.

In some applications, it may be preferred for the expansion andcompression of the thermal cell array unit to occur with a smooth,predictable and repeatable motion. There are a number of methods bywhich the thermal cell array unit can be physically positioned and/orsupported in order to result in the desired smooth, predictable andrepeatable motion. While particular methods of physically positioningand/or supporting the thermal cell array unit have been described here,it is to be understood that other methods of physically positioningand/or supporting the thermal cell array unit are possible and areintended to be included herein.

In a first example, FIG. 15 depicts thermal cell array unit 1501contained within enclosed panel 1500. Drive wires 1502 are attached tothermal cell array unit 1501 by connecting drive wires 1502 to frontplate 1503. Drive wires 1502 may be installed with sufficient tension toadequately support thermal cell array unit 1501, thereby resulting inthe desired smooth, predictable and repeatable motion. The tension ofdrive wires 1502 may be controlled by incorporation of an appropriatespring or other tension-controlling element.

In another example, FIG. 18 depicts a method of supporting a thermalcell array unit using low-friction sliding or rolling elements 1802 aand 1802 b. In this example depicted in FIG. 18, thermal cell array unit1801 is contained within enclosed panel 1800. Low-friction elements 1802a and 1802 b are adhered or otherwise attached at or near the bottom offront plate 1804. Low friction elements 1802 a and 1802 b make physicalcontact with frame element 1803 and ensure that thermal cell array unitis appropriately positioned against or near frame element 1803 andfurther ensure smooth, predictable, and repeatable motion of thermalcell array unit 1801. Low friction elements 1802 a and 1802 b may besliding or rolling elements.

In another example, FIG. 19 depicts a method of supporting a thermalcell array unit using hanging supports. In this example depicted in FIG.19, thermal cell array unit 1901 is contained within enclosed panel1900. Hanging support elements 1902 a and 1902 b are adhered orotherwise attached at or near the top of front plate 1904. Frame element1903 comprises linear grooves 1905 a and 1905 b. Hanging supportelements 1902 a and 1902 b contain end features 1906 a and 1906 b,respectively. End features 1906 a and 1906 b slide, with low friction,within grooves 1905 a and 1905 b respectively. Low friction sliding ofend features 1906 a and 1906 b within grooves 1905 a and 1905 b ensurethat the thermal cell array unit is appropriately positioned against ornear frame element 1903 and further ensure smooth, predictable andrepeatable motion of thermal cell array unit 1901. Hanging supportelements 1902 a and 1902 b guide the motion of thermal cell array unit1901. Motion may be caused by one of the position control approachesdescribed earlier, or other suitable position controller. The thermalcell array unit may have additional support elements (not shown)positioned at or near the bottom of front plate 1904.

In another example, FIG. 20 depicts a method of supporting a thermalcell array unit using a centrally-located wire. In this example depictedin FIG. 20, thermal cell array unit 2001 is contained within enclosedpanel 2000. Support wire 2002 is suspended between frame elements 2005and 2006. Support wire 2002 passes through hole 2003, where hole 2003forms a passage for support wire 2002 through both front plate 2004 andthermal cell array unit 2001. Support wire 2002 is suspended betweenframe elements 2005 and 2006 with appropriate tension such that supportwire 2002 adequately positions and supports thermal cell array unit 2001and further ensures smooth, predictable, and repeatable motion ofthermal cell array unit 2001.

In some applications, it may be preferred for the front plate attachedto the thermal cell array to have a particular shape or configuration,depending on desired operational or orientational characteristics. FIGS.21A-C depict several example front plate designs. FIG. 21A depicts afront elevation view of front plate 2100. Front plate 2100 is formedfrom a continuous, solid rectangular sheet material. The preferredthickness of front plate 2100 depends on the degree of flexibility,weight, and/or structural rigidity that is required for the particularapplication. FIG. 21B depicts a front elevation view of a front plateassembly consisting of two components. Front plate component 2101 aattaches to one edge of the thermal cell array (not shown) and frontplate component 2101 b attaches to a second, opposite, parallel edge ofthe thermal cell array (not shown). Front plate components 2101 a and2101 b are fabricated from rigid members or material. This embodimentmay be preferred in situations where a high degree of flexibility orconformability of the thermal cell array unit front plate is required.FIG. 21C depicts a front elevation view of front plate 2102. Front plate2102 is formed from a rectangular sheet material. Front plate 2102contains cut-out regions 2103. Cut-out regions 2103 may be formed byremoving material from a previously continuous, solid sheet as depictedin FIG. 21A. The preferred thickness of front plate 2102 and thepreferred size, number, and spatial location of cut-out regions 2103depend on the degree of flexibility, weight, and/or structural rigiditythat is required for the particular application. While particularexamples of front plate designs have been described here, it is to beunderstood that other front plate designs are possible and are intendedto be included herein.

Alternatively, rather than utilizing a mechanical position controller totransition the array unit between the compressed and expanded states, anelectrostatic position controller may be utilized. Example electrostaticposition controller are described with reference to FIGS. 22 through 24.

FIG. 22A and 22B show a cross-sectional view of a portion of a thermalcell array unit, such as the thermal cell array unit 100 describedabove, that incorporates an electrostatic position control or actuationsystem. The portion shown in FIGS. 22A and 22B includes a cross-sectionof one longitudinally extending cavity 2200. The cavity 2200 is formedby two adjacent layers of thin, flexible film 2201 and 2203 that arebonded in selected regions 2205 a and 2205 b, similar to the films 120a, 120 b that are bonded in bonding region 130 as described above. Thecavity 2200 is shown in the expanded state in FIG. 22A and in thecompressed state in FIG. 22B.

Films 2201 and 2203 may have a thickness of less than 40 microns anddesirably the thickness may be less than 10 microns. The films 2201 and2203 may be layers of thin, flexible film material formed from, forexample, polyester film, Mylar, or any highly electrically insulativefilm. Films 2201 and 2203 are coated on one side by a thin electrodecoating 2202 and 2204. Thin electrode coating 2202 and 2204 may be madeof a metal or other low emissivity and electrically conductive material,such as, for example, aluminum. The thermal emissivity of the materialdesirably is less than 0.2 and more desirably is less than 0.05. Thinelectrode coatings 2202 and 2204 are separated by at least one of lowelectrical conductivity films 2201 and 2203 such that the coatings donot contact each other when the cavity 2200 is in the compressed state,as shown in FIG. 22A. In the example shown in FIG. 22A, electrodecoating 2202 is coated on the inner (right-most) surface of film 2201and electrode coating 2204 is coated in the outer (again, right-most)surface of film 2203.

FIG. 22B shows the cavity 2200 in a compressed state. In the compressedstate, the cavity 2200 is compressed along an axis perpendicular to thelongitudinal axis of the bonding regions 2205 a and 2205 b (which is thehorizontal direction in the view shown in FIGS. 22A and 22B) by applyingan electrical potential difference between thin electrode coatings 2202and 2204 to generate an attractive electrical force between the films2201 and 2203. The magnitude of the applied electrical potentialdifference depends on a number of factors, including the thickness offilms 2201 and 2203, and the conductivity of thin electrode coating 2202and 2204. The magnitude of the applied voltage may be, for example, 1000V, and possibly as high as 3000 V. While the voltage level is high,there is negligible current flow through the electrostatic systembecause the coatings 2202 and 2204 are separated by at least one of thelayers 2201 and 2203. As well, the electrical components required toprovide this voltage level with negligible current flow are inexpensiveand readily available. The voltage may be applied by, connecting arespective electrode (not shown) to each of the coatings 2202 and 2204at, for example, an edge of each of the layers 2201 and 2203. If films2201 and 2203 are too thick, they will be too rigid to form thecompressed state shown in FIG. 22B with the electrostatic pressure thatcan be achieved by application of a practical magnitude of voltage. Aswell, if film 2201 is too thick, the separation distance betweenelectrically conductive coatings 2202 and 2204 will be too great. Iffilms 2201 and 2003 are too thin, they will not be sufficientlymechanically robust for long-term device performance. The desiredperformance can be achieved with a range of thicknesses of films 2201and 2203, with the preferred thickness being approximately 10 microns.

The electrostatic position control or actuation system shown in FIG. 22Aand 22B is effective because, while material comprising films 2201 and2203 is a good electrical insulator, the air within the cavity 2200 thatseparating films 2201 and 2203 is not a good electrical insulator.Typically, an air gap between two electrodes can withstand an electricfield of approximately 106 V/m. Fields larger than this will result inelectric breakdown across the air gap. In contrast, a typical goodelectrical insulator suitable for providing films 2201 and 2203 canwithstand an electric field of at least 107 V/m. The electrostaticpressure associated with the electric field (i.e. the force per unitarea) varies with the square of the magnitude of the electric field, andso this means that the maximum force per unit area of attractionassociated with an air gap is 100 times weaker than the maximum forcefor an insulator.

The electrostatic position control or actuation system described abovetakes advantage of the so-called Paschen effect, whereby the breakdownof the electric field of air in gaps that have a thickness comparable tothe mean free path of an ion in the air is up to ten times higher. Inother words, a very thin air gap (for example, less than 0.5 micronsthick) can withstand an electric field of 10⁷ V/m. Referring to theexample shown in FIG. 22A and 22B, when an electrical potential isapplied between electrode coatings 2202 and 2204, the electric field ishighest within the narrow gap regions labeled as 2206 and 2207 where thefilms are close to the point of contact. In these very narrow regions2206 and 2207, the conditions for the Paschen effect are met, and theforce per unit area of attraction is very high. The films are attractedinto contact in this region, and the narrow area of high fieldpropagates along the film. In the example shown in FIG. 22A, the pointsof contact of films 2201 and 2203 move vertically from each point 2206and 2207 towards the middle of the cavity 2200, as the devicetransitions from the expanded state shown in FIG. 22A to the compressedstate shown in FIG. 22B.

Removing the electrical potential difference previously applied betweenthin electrode coatings 2202 and 2204 restores the expanded state. Thereare a number of mechanisms by which the expanded state shown in FIG. 22Ais restored. For example, the expanded state may be restored by applyingair or gas pressure to the previously compressed element, therebyinflating the element. The expanded state may be restored by forming thefilms 2201 and 2202 from a material having an inherent spring-likenature. This inherent spring-like nature may be created by exposingfilms 2201 and 2202 to heat treatment or chemical treatment in order todeform films 2201 and 2202 into the desired expanded shape depicted inFIG. 22A. The expanded state may further be restored by using anadditional spring-like element, as will be described in reference toFIGS. 23A and 23B.

FIG. 23A and 23B show the cavity 2200 of FIGS. 22A and 22B that includesa biasing element 2303. In the expanded state shown in FIG. 23A, thebiasing element 2303 applies a force to the films 2201 and 2203 suchthat the expanded state is achieved. The biasing element 2303 could be,for example, a thin spring steel or other thin shim stock that exhibitsa spring-like mechanical characteristic when moderately deformed. Theelectrostatic force caused by the coatings 2202 and 2204 when intransition from the expanded to the compressed states is less than theforce that would permanently deform the biasing element 2303.

FIG. 23B shows the cavity 2200 in the compressed state, which isachieved by applying an electrical potential difference between thinelectrode coatings on films 2201 and 2203. The electrostatic force issufficient to temporarily deform biasing element 2303. The magnitude ofthe applied electrical potential difference depends on a number offactors, including the thickness of films 2201 and 2203, theconductivity of the thin electrode coatings 2202 and 2204, and the forcerequired to compress the biasing element 2303. Removing the electricalpotential difference previously applied between thin electrode coatings2202 and 2204 removes the deformative compressive force on biasingelement 2303. The biasing element 2303 expands to its undeformed state,thereby separating films 2201 and 2203 and restoring the expanded state,shown as in FIG. 23A.

FIGS. 24A and 24B depicts a top cross-sectional view of full thermalcell array unit 2400 that incorporates the electrostatic positioncontrol or actuation system described above. Similar to the array unit100 described above, the array unit 2400 is formed by multiple adjacentlayers of thin, flexible film 2401 a-k that are bonded in selectedregions 2430 such that when the array unit is expanded it forms aplurality of air-enclosing pockets 2410, which are substantially similarto cavity 2200. Each of films 2401 a-k are coated on one side by a thinelectrode coating as described above such that, for each adjacent pairof films, such as films 2401 a and 2401 b, the thin electrode coatingsare separated by at least one of low electrical conductivity films 2401a and 2401 b. Surface sheets 2440 and 2450 are bonded to the thermalcell array unit formed by the assembly of films 2401 a-k.

FIG. 24B depicts a top cross-sectional view of the array unit 2400 inthe compressed state. Array unit 2400 is compressed along an axisperpendicular to the longitudinal axis of the bonding regions 2430 byapplying an appropriate electrical potential difference between adjacentthin electrode coatings as described above. Removing the electricalpotential difference previously applied between the thin electrodecoatings restores the expanded state.

The fully compressed state shown in FIG. 24B is facilitated by applyingan appropriate electrical potential difference between adjacent pairs ofthin electrode coatings, where an appropriate electrical potentialdifference is sufficient to compress the structure to the desiredcompression state. The magnitude of the applied electrical potentialdifference depends on a number of factors including, for example, thethickness of films 2401 a-k and the conductivity of thin electrodecoating. The thin electrode coatings on films 2401 a-k may be maintainedat different electrical potentials, such that individual cavities 2410within array unit 2400 may be maintained in an expanded state whileother cavities 2410 are maintained in a compressed state, as desired.

In some embodiments, the adjacent thin, flexible films forming thermalcell array unit may exhibit a high sticking force in the compressedstates shown in FIGS. 22A, 23A, and 24A. This high sticking force maymake it more difficult for the expanded state to be restored when theapplied electrical potential difference is removed. In these cases, itmay be desirable to reduce the overall area of surface contact betweenadjacent films. This reduction of overall area of surface contact may beachieved by a number of approaches. One such approach involves texturingthe surface of one or both adjacent films such that the surface retainssmall features, typically in the size range of 1-100 nanometers.Examples of surface texturing approaches include: applying a coating ofvery small beads or other particulates, embossing very small surfacefeatures, or scratching or abrading the surface.

The appropriate method of causing the thermal cell array unit to expandand compress with a smooth, predictable, and repeatable motion may bedifferent than as described in the preceding examples, depending on anumber of factors, including but not limited to: the size and shape ofthe enclosed panel, the orientation of the enclosed panel within abuilding structure, the intended purpose of the panel, and the desiredoperational characteristics of the panel.

While the embodiments described above illustrate the thermal cell arrayunits or assemblies and enclosed panels having particular shapes oroperational or structural features, the skilled person will understandthat the thermal cell array units or assemblies may have any number ofsuitable shapes or operational or structural features sufficient toperform the operations described above.

In addition, while not shown in the figures, it is to be understood thatthe transition of the foregoing thermal cell array units betweencompressed and expanded states can be achieved by any suitablemechanical, electro-mechanical, or other position transitioning device.For example, the thermal cell array units may be coupled to each otherand actuated by a control rod to transition the thermal cell array unitsbetween compressed and expanded states. In another example, anelectro-mechanical actuator could be employed to automate thetransitioning of the thermal cell array unit between compressed andexpanded states. In another example, the thermal cell array units couldbe positioned by means of a manual or physical control element.

It is noted that the various embodiments of the thermal cell array unitor system, as described above, and their combinations, can be used in agreenhouse, glasshouse, or other building structure. Further, thethermal cell array unit may also be expanded or compressed either bymanual operation or by automatic control in response to the output of asensor detecting a selected parameter, such as a sunlight or temperaturemeasurement sensor.

The thermal cell array units and assemblies described above can be usedin a greenhouse, glasshouse, solarium, or other building structure, toincrease the thermal insulation to reduce heat loss from the building.The thermal cell array units and assemblies described above can furtherbe used in walls and doors of refrigeration units or other cold-storageappliances where it is desirable to have a high degree of visualtransparency in some instances and a high degree of thermal insulationin other instances. The thermal cell array units and assemblies canfurther be used in walls or roofs of building structures where variablethermal insulation may be desired or required. The thermal cell arrayunits and assemblies described above can further be used in conjunctionwith thermal storage units, assemblies, or assemblies. Thermal cellarray units and assemblies described above can further be used in solarheat capture structures.

FIGS. 25A, 25B, and 25C illustrate a building structure, greenhouse2500, according to an embodiment. As shown in the figures, thegreenhouse 2500 is a structural building having upstanding walls 2501and an isosceles peaked roof 2502, which enclose an inside greenhousespace 2503 therein. The walls 2501 may be transparent or opaque, and adoor (not shown) can be provided on one of the walls 2501 for access tothe inside space. The roof 2502 and walls 2501 can be made of differenttypes of materials, such as glass or plastic, including but not limitedto polyethylene film, multiwall sheets of polycarbonate material,ethylene tetrafluoroethylene sheet, or PMMA acrylic glass. The roof 2502and walls 2501 can be self-supported or installed onto a supportiveframe. The greenhouse 2500 heats up because incoming visible solarradiation (for which the glass or plastic is transparent) from the sunis absorbed by plants, soil, and other things inside the building. Airwarmed by the heat from hot interior surfaces is retained in thebuilding by the roof and walls. In this embodiment, the roof 2502comprises two sections 2502 a and 2502 b which form an isoscelestriangle shape in cross-section as shown in FIG. 25A. Sections 2502 aand 2502 b of the roof 2502 comprise a thermal cell array unit.Specifically, the size and dimensions of the above-described thermalcell array unit are tailored to fit into the building structure, suchthat the thermal cell array unit forms and functions as section 2502 aand 2502 b of the roof 2502.

While in this embodiment, only sections 2502 a and 2502 b of the roof2502 is integrated with the thermal cell array unit, one or more thermalcell array units/assemblies can be formed as part of the walls 2501.

FIG. 26 depicts a greenhouse structure such as the one described withreference to FIGS. 25A, 25B, and 25C. Enclosed panels 2601 a, 2601 b,2601 c, 2601 d, 2601 e, and 2601 f are supported by structural roofelements (not shown). Enclosed panels 2601 a, 2601 b, 2601 c, 2601 d,2601 e, and 2601 f are positioned inside the greenhouse, adjacent theinterior surfaces of the transparent window elements (not shown) thatform the planar surface of the greenhouse roof In the embodimentdepicted in FIG. 26, enclosed panels 2601 a, 2601 b, 2601 c, 2601 d,2601 e, and 2601 f are protected by the adjacent transparent windowelements that form the surface of the greenhouse roof and therefore areprotected from wind, rain, and dirt. In some embodiments, it may bepreferable for enclosed panels 2601 a, 2601 b, 2601 c, 2601 d, 2601 e,and 2601 f to form the exterior structure of the greenhouse, rather thanbeing supported by the exterior structure of the greenhouse. In theseembodiments where enclosed panels form the exterior structure of thegreenhouse, the enclosed panels would not be protected from the elementsby an exterior transparent window within the greenhouse structure.Rather, the exterior-facing transparent face of the enclosed planeswould form the exterior transparent window of the greenhouse structure.Accordingly, the enclosed panels must have sufficient structuralrigidity as would be expected for a greenhouse structure.

FIGS. 27A, 27B, and 27C illustrate a building structure, greenhouse2700, according to an embodiment. As shown in the figures, thegreenhouse 2700 is a structural building having upstanding walls 2701and a sawtooth peaked roof 2702, which enclose an inside greenhousespace 2703 therein. The walls 2701 may be transparent or opaque, and adoor (not shown) can be provided on one of the walls 2701 for access tothe inside space. The roof 2702 and walls 2701 can be made of differenttypes of materials, such as glass or plastic, including but not limitedto polyethylene film, multiwall sheets of polycarbonate material,ethylene tetrafluoroethylene sheet, or PMMA acrylic glass. The roof 2702and walls 2701 can be self-supported or installed onto a supportiveframe. The greenhouse 2700 heats up because incoming visible solarradiation (for which the glass or plastic is transparent) from the sunis absorbed by plants, soil, and other things inside the building. Airwarmed by the heat from hot interior surfaces is retained in thebuilding by the roof and walls. In this embodiment, the roof 2702comprises two sections 2702 a and 2702 b which form a sawtooth shape incross-section as shown in FIG. 27A. The section 2702 b of the roof 2702comprises a thermal cell array unit. Specifically, the size anddimensions of the above-described thermal cell array unit are tailoredto fit into the building structure, such that the thermal cell arrayunit forms and functions as section 2702 b of the roof 2702.

While in this embodiment, only section 2702 b of the roof 2702 isintegrated with the thermal cell array unit, one or more thermal cellarray units/assemblies can be formed as the entire roof 2702. Further,one or more thermal cell array units/assemblies may also be formed aspart of the walls 2701.

FIGS. 28A, 28B, and 28C illustrate a building structure, greenhouse2800, according to an embodiment. As shown in the figures, thegreenhouse 2800 is a structural building having upstanding walls 2801and a curved roof 2802, which enclose an inside greenhouse space 2803therein. The walls 2801 may be transparent or opaque, and a door (notshown) can be provided on one of the walls 2801 for access to the insidespace. The roof 2802 and walls 2801 can be made of different types ofmaterials, such as glass or plastic, including but not limited topolyethylene film, multiwall sheets of polycarbonate material, ethylenetetrafluoroethylene sheet, or PMMA acrylic glass. The roof 2802 andwalls 2801 can be self-supported or installed onto a supportive frame.The greenhouse 2800 heats up because incoming visible solar radiation(for which the glass or plastic is transparent) from the sun is absorbedby plants, soil, and other things inside the building. Air warmed by theheat from hot interior surfaces is retained in the building by the roofand walls. In this embodiment, the roof 2802 forms a semi-circular shapein cross-section as shown in FIG. 28A. The roof 2802 comprises a thermalcell array unit. Specifically, the size and dimensions of theabove-described thermal cell array unit are tailored to fit into thebuilding structure, such that the thermal cell array unit forms andfunctions as roof 2802.

While in this embodiment, the roof 2802 forms both the roof 2802 and thewalls 2801 of the structure. The roof 2802 and walls 2801 are integratedwith the thermal cell array unit, and one or more thermal cell arrayunits/assemblies can be formed as the entire roof 2802. In otherembodiments, the thermal cell array unit may not be integrated intowalls 2801.

According to some other embodiments, one or more above-described thermalcell array units/assemblies can be positioned below a transparent roofstructure or adjacent one or more transparent walls, such that thethermal cell array units/assemblies can be opened to allow thetransmission of sunlight into the structure and closed to prevent thetransmission of sunlight into the structure and also to increase thethermal insulation property of the roof or walls. The thermal cell arrayunits can be attached to the support structure of the greenhouse,glasshouse, or other building structure. For example, when positionedbelow the roof, the thermal cell array unit/system can be suspendedhorizontally near the roof However, it is noted that the orientation ofthe thermal cell array unit/system can be adjusted depending on variousfactors, such as the structure and layout of the building, or maximumreceipt of sunshine. Alternatively, the thermal cell arrayunits/assemblies can also be positioned near the roof and/or walls fromoutside of the building.

As described earlier with reference to FIGS. 10A through 10C, the meansof position controller causes the first of the two surface sheets tomove in a direction that is normal to the sheet while maintaining thesecond of the two surface sheets primarily parallel to the first sheet.It may also be desirable for the position controller coupled to thesurface sheets of the thermal cell array unit to be arranged such thatwhen the control force is applied, one or both of the first and secondsurface sheets move in a pivoting motion. Specifically, one or both ofthe surface sheets pivot whereby a first end of the one of the first andsecond surface sheet is substantially fixed relative to a correspondingfirst end of the other of the first and second surface sheets, and asecond end of the one of the first and second surface sheets, oppositethe first end, moves relative to the second end of the other of thefirst and second surface sheets.

One example of thermal cell array units arranged to move in a pivotingmotion is depicted in FIGS. 29A and 29B. FIG. 29A shows a top-downcross-sectional view of multiple thermal cell array units in theirexpanded state within an enclosed panel. In the example shown in FIG.29A, enclosed panel 2900 is formed by side frame elements 2907 and 2909and front and back panels 2908 and 2910. Enclosed panel 2900 containssix thermal cell array units 2901, 2902, 2903, 2904, 2905 and 2906. Inthe example enclosed panel 2900, thermal cell array units 2901-2906 areexpanded to substantially fill the volume within enclosed panel 2900. Asan example, surface sheet 2914 of thermal cell array unit 2903 ismaintained in a vertical orientation. Surface sheet 2913 undergoes apivoting motion whereby one edge of surface sheet 2913 is held close tothe corresponding edge of the surface sheet 2914 forming vertex 2911,and the other edge of surface sheet 2913 is moved away from surfacesheet 2914. This pivoting expansion motion for thermal cell array units2901-2906 results in the volume 2913 of the enclosed panel beingsubstantially occupied by the expanded thermal cell array units2901-2906.

FIG. 29B shows the compressed state for thermal cell array units2901-2906 whereby the volume 2913 of the enclosed panel is substantiallyunoccupied by the compressed thermal cell array units 2901-2906. Anadvantage of the pivoting motion embodiment is that it restricts themotion of the surface sheet to one degree of freedom which may simplifythe operation of the positioning means. As well, a pivoting motion cangenerally be achieved using low friction hinges which could result inless force required to expand and compress the thermal cell array unit.

As described earlier with regard to FIGS. 1A and 1B, a thermal cellarray may comprise a plurality of similarly sized flexible sheets 120a-k of thin film arranged in a stacked arrangement with pairs of sheetsbonded to form continuous array of thermal cells 110. In an alternateembodiment, a thermal cell array may comprise individual thermal cellsas depicted in the top cross-sectional views in FIGS. 30A and 30B.

In FIG. 30A, thermal cell array unit 3000 comprises a plurality ofindividual thermal cells 3010, each consisting of two flexible filmselements 3050 and 3060 having two edge-bond zones 3020 that compriseless than 20% and preferably less than 5% of the film area. Edge-bondzones 3020 run parallel to the longitudinal direction along each of thethermal cells 3010. Thermal cell array unit 3000 is formed by bondingstacks of thermal cells 3010 along a central bond zone 3040. Centralbond zone 3040 comprises less than 20% and preferably less than 5% ofthe surface area of thermal cell 3010 and runs parallel to thelongitudinal direction along the center of thermal cells 3010. Aplurality of stacks of thermal cells 3010 are placed side by side so asto occupy most of the available area between surface sheets 3070 and3080. Stacks of thermal cells 3010 are bonded to surface sheets 3070 and3080 along the central bond zone 3040. Prior to bonding sufficientlylarge gap 3030 is maintained between thermal cells 3010 to ensure thatthe adjacent thermal cells 3010 do not make contact with one anotherwhen surface sheets 3070 and 3080 are brought close to one another inthe compressed state. FIG. 30A shows thermal cell array unit 3000 in theexpanded state.

FIG. 30B shows thermal cell array unit 3000 in the compressed state. Theindividual thermal cells enable thermal cell array unit 3000 to beexpanded and compressed without requiring any regions of the sheetsforming the thermal cell array unit to stretch or otherwise deform. Insome applications, stretching or otherwise irreversibly deforming thesheets may reduce the long-term performance capability of the thermalcell array unit and in these cases it would be advantageous to employindividual thermal cells as described with reference to FIGS. 30A and30B.

In the example shown in FIGS. 30A and 30B, individual thermal cells arebonded to one another. In an alternate example shown in FIGS. 31A and31B, thermal cell array unit 3100 is formed by individual thermal cells3110 that are bonded to and separated by thin, flat sheets 3140. Sheets3140 may provide lateral stability and prevent undesirable lateralmotion of stacks of thermal cells 3110 during the controlled movement ofsurface sheets 3170 and 3180 to expand and compress thermal cell arrayunit 3100. FIG. 31A shows thermal cell array unit 3100 in the expandedstate. FIG. 31B shows thermal cell array unit 3100 in the compressedstate.

While particular embodiments have been described in the foregoing, it isto be understood that other embodiments are possible and are intended tobe included herein. It will be clear to any person skilled in the artthat modifications of and adjustments to the foregoing embodiments, notshown, are possible. Further, it is to be understood that the foregoingembodiments may be applied in a variety of applications, such as, forexample, greenhouses, solar heat capture structures, commercial orresidential skylights and windows, walls and doors of refrigerationunits or other cold-storage appliances, or for other suitable structuresand applications.

1. A variable thermal insulation assembly comprising: a frame thatcircumscribes a thermal actuation region having a gas; one or morethermal cell array units positioned within the thermal actuation region,each thermal cell array unit comprising: a first surface sheet and asecond surface sheet, wherein the first and second surface sheets aresimilarly shaped and define a thermal cell array region therebetween; athermal cell array positioned within each thermal cell array region andcoupled to the first and second surface sheets such that the thermalcell array substantially fills the thermal cell array region; whereineach thermal cell array comprises a plurality of sheets and at least twoof the sheets in each thermal cell array are flexible sheets; whereinadjacent pairs of said flexible sheets are bonded together along atleast one pair of bonding regions that extend substantially parallel toeach other such that each pair of flexible sheets defines at least onesubstantially longitudinally symmetrical cavity between each pair ofbonding regions, each longitudinally symmetrical cavity being one of aplurality of thermal cells; wherein a distance between each pair ofbonding regions is sufficiently small such that the total heat lossarising from convective gas flow within the thermal cells is less thantotal heat loss arising from thermal conduction of the gas presentwithin the thermal actuation region; wherein the distance between eachpair of bonding regions is sufficiently large, and the thermalconductivity of the sheets is sufficiently low, such that heat transferdue to thermal conduction within the sheets is less than the heat lossdue to thermal conduction of the gas of the thermal actuation region;wherein each of the plurality of thermal cells is bonded to anotherthermal cell or a sheet in order to form a connected thermal cell arrayunit; a position controller coupled to at least one of the first andsecond surface sheets for applying a control force on at least one ofthe first and second surface sheets to expand the thermal cell arrayinto an expanded state and compress the thermal cell array into acompressed state within the thermal actuation region to vary a volume ofthe thermal actuation region that is occupied by the thermal cell arrayunits; wherein the plurality of sheets are sufficiently thin and formedof one or more materials that are sufficiently compliant such that, foreach first and second sheet, when the thermal cell arrays are in theexpanded state by the applied control force, a gap between each surfacesheet and the adjacent frame surface or surface sheet, is madesufficiently small such that the total heat loss that is attributable togas flow through the gap is less than the total of the heat loss due tothermal conduction through the thermal cells.
 2. The variable thermalinsulation assembly of claim 1, wherein the position controller iscoupled to the one of the first and second sheets such that, when thecontrol force is applied, the at least one of the first and the secondsurface sheets move in a direction that is normal to the one of thefirst and second surface sheet such that, during the moving the firstand second surface sheets are maintained substantially parallel to eachother.
 3. The variable thermal insulation assembly of claim 1, whereinthe position controller is coupled to the one of the first and secondsurface sheets such that, when the control force is applied, the one ofthe first and second surface sheets pivots whereby a first end of theone of the first and second surface sheet is substantially fixedrelative to a corresponding first end of the other of the first andsecond surface sheets, and a second end of the one of the first andsecond surface sheets, opposite the first end, moves relative to thesecond end of the other of the first and second surface sheets.
 4. Thevariable thermal insulation assembly of claim 1, wherein at least someof the plurality of sheets comprising the thermal array are coated on atleast a first side by a layer of material having a thermal emissivity ofless than 0.2.
 5. The variable thermal insulation assembly of claim 4,wherein the material is aluminum.
 6. The variable thermal insulationassembly of claim 1, wherein each of the plurality of sheets comprisingthe thermal array has a curved shape, and the plurality longitudinallyextending regions follow the curved shaped such that the formedlongitudinally extending cavities have the curved shape.
 7. The variablethermal insulation assembly of claim 1, wherein the frame comprises edgeelements that circumscribe the thermal actuation region, and a frontpanel and a back panel coupled to the edge elements to form an enclosedpanel that encloses the array.
 8. The variable thermal insulationassembly of claim 7, wherein the front panel and back panel arelight-transmitting window elements that are fabricated from one ofglass, mylar, acrylic, polycarbonate, polyethylene, or ethylenetetrafluoroethylene.
 9. The variable thermal insulation assembly ofclaim 8 wherein light-transmitting window elements are diffuselylight-transmitting elements.
 10. The variable thermal insulationassembly of claim 1, wherein the front panel and the back panel are eachformed from a thin, light-transmitting material, wherein the front paneland the back panel are bonded together in a periphery region to define apillow-shaped cavity within the enclosed panel.
 11. The variable thermalinsulation assembly of claim 10, wherein the thin, light transmittingmaterial is one of polyethylene, polycarbonate, or ethylenetetrafluoroethylene. 12-14. (canceled)
 15. The variable thermalinsulation assembly of claim 7, wherein an inner surface of at least oneedge element has a reflectivity of at least 80%.
 16. (canceled)
 17. Thevariable thermal insulation assembly of claim 1, wherein the framecomprises a first end element at the first end, a second end element atthe second end, and a pair of side elements that connect the first andsecond end elements, wherein at least one of the side elements includesa seal element for inhibiting airflow through an opening of theplurality of longitudinally extending cavities adjacent to the sideelement when the array is in the expanded state.
 18. The variablethermal insulation assembly of claim 17, wherein the seal element is afirst inflatable bladder.
 19. (canceled)
 20. (canceled)
 21. The variablethermal insulation assembly of claim 1, wherein the position controlleris an electrostatic system wherein: the plurality of flexible sheets ofthe thermal cell array are formed of an electronically insulativematerial that is coated on one side with an electrically conductivematerial such that, for each pair of flexible sheets, the electricallyconductive material coating of each flexible sheet of the pair areseparate by at least one layer of the electrically insulative material;the variable thermal insulation assembly further comprising: acontroller to apply an electric potential difference between eachadjacent pairs of sheets such that the electrically conductive coatingsof the adjacent pair of sheets attract each other to cause the array tobe in the compressed state; and a plurality of biasing elements locatedwith the plurality of longitudinally extending cavities to bias adjacentpairs of sheets away from each other to cause the array to be in theexpanded state in the absence the controller applying an electricalcharge. 22-53. (canceled)
 54. The variable thermal insulation assemblyof claim 8, wherein the light-transmitting window elements have a firstportion that is diffusely light transmitting and a second portion thatis non-diffusely light transmitting such that the diffusioncharacteristics of the transmitted light can be controlled.
 55. Thevariable thermal insulation assembly of claim 1, wherein each thermalcell consists of two flexible film elements, each flexible film elementhaving two edge-bond zones that comprise less than 20% of a surface areaof the flexible film element, each edge-bond zone extending in adirection parallel to the longitudinal direction of the flexible filmelement, and a central bond zone comprising less than 20% of the surfacearea and extending parallel to the longitudinal direction along thecenter of the flexible film element, wherein each thermal cell is formedby bonding two flexible film elements along the edge bond zones, andwherein thermal cell are oriented into stacks for which each thermalcell is bonded to an adjacent thermal cell along the central bond zone,and wherein a plurality of said stacks are oriented within the thermalcell region such that the stacks do not make contact with one anothereven when thermal cell array unit is in the compressed state.
 56. Thevariable thermal insulation assembly of claim 55, wherein additionalthin sheets similar in size and shape to the first and second surfacesheets, are positioned within said stacks and bonded there along thefilm element central bond zones, in order to stabilize the stacksagainst lateral motion within the stack during controlled movement ofthe first and/or second sheets.
 57. The variable thermal insulationassembly of claim 1, wherein the plurality of sheets are sufficientlythin and formed of one or more materials that are sufficiently compliantsuch that an average size of the gap, when the thermal cell array is inthe expanded state, is less than 5 mm.
 58. The variable thermalinsulation assembly of claim 3, wherein the frame further comprises edgeelements that circumscribe the thermal actuation region, and a frontpanel and a back panel coupled to the edge elements to form an enclosedpanel that encloses the array.
 59. The variable thermal insulationassembly of claim 3, wherein the position controller is an electrostaticsystem wherein: the plurality of flexible sheets of the thermal cellarray are formed of an electronically insulative material that is coatedon one side with an electrically conductive material such that, for eachpair of flexible sheets, the electrically conductive material coating ofeach flexible sheet of the pair are separate by at least one layer ofthe electrically insulative material; the variable thermal insulationassembly further comprising: a controller to apply an electric potentialdifference between each adjacent pairs of sheets such that theelectrically conductive coatings of the adjacent pair of sheets attracteach other to cause the array to be in the compressed state; and aplurality of biasing elements located with the plurality oflongitudinally extending cavities to bias adjacent pairs of sheets awayfrom each other to cause the array to be in the expanded state in theabsence the controller applying an electrical charge.
 60. The variablethermal insulation assembly of claim 7, wherein the position controlleris an electrostatic system wherein: the plurality of flexible sheets ofthe thermal cell array are formed of an electronically insulativematerial that is coated on one side with an electrically conductivematerial such that, for each pair of flexible sheets, the electricallyconductive material coating of each flexible sheet of the pair areseparate by at least one layer of the electrically insulative material;the variable thermal insulation assembly further comprising: acontroller to apply an electric potential difference between eachadjacent pairs of sheets such that the electrically conductive coatingsof the adjacent pair of sheets attract each other to cause the array tobe in the compressed state; and a plurality of biasing elements locatedwith the plurality of longitudinally extending cavities to bias adjacentpairs of sheets away from each other to cause the array to be in theexpanded state in the absence the controller applying an electricalcharge.
 61. A variable thermal insulation assembly comprising: at leastone array comprising a plurality of sheets of film, wherein theplurality of sheets are in a stacked arrangement and each sheet isbonded to an adjacent sheet along a plurality of longitudinallyextending regions such that each pair of adjacent sheets form aplurality of longitudinally extending cavities between adjacent regionsof the adjacent sheets; a support frame comprising end elements, whereinthe support frame frames the plurality of sheets, wherein support frameis coupled to the array to support the array such that the array maytransition between: an expanded state in which the array is expanded byextending a front side of the array within a plane of the supportingframe in a direction from a first end of the support frame to a secondend of the support frame, the direction being perpendicular to alongitudinal axis of the longitudinally extending regions, such that thelongitudinally extending cavities are expanded to provide thermalinsulation over the support frame; and a compressed state in which thearray is compressed within the plane of the frame along the directionperpendicular to the longitudinal axis such that the longitudinallyextending cavities are compressed; wherein in the expanded state, thefront edge conforms to one of the second end of the support frame or asecond front edge of a second array to form a seal that inhibits airflow between the front edge and the one of the second end of the supportframe or the second front edge of the second array.